**Core Concept**
Radial keratoneuritis is an inflammatory condition of the cornea characterized by the formation of inflammatory cells and blood vessels in the radial nerves of the cornea. This condition is often associated with uveitis and is a potential indicator of underlying systemic diseases.

**Why the Correct Answer is Right**
Radial keratoneuritis occurs due to the infiltration of inflammatory cells into the corneal parenchyma, leading to the destruction of the corneal nerves. This results in the formation of radial keratic precipitates and the subsequent growth of new blood vessels. The condition is often seen in conjunction with anterior uveitis, particularly in patients with sarcoidosis, tuberculosis, or other autoimmune diseases. The presence of radial keratoneuritis can indicate the activity of the underlying disease and the need for aggressive treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the condition of radial keratoneuritis.
**Option B:** This option is incorrect as it is a different condition that affects the cornea, but does not involve the radial nerves.
**Option C:** This option is incorrect as it is not a specific disease associated with radial keratoneuritis.

**Clinical Pearl / High-Yield Fact**
Radial keratoneuritis is a key indicator of underlying systemic diseases, particularly sarcoidosis and tuberculosis. The presence of this condition in a patient with uveitis should prompt a thorough investigation for systemic disease.

**Correct Answer: D. Sarcoidosis**